This invention relates generally to surgical equipment, and more particularly to a surgical device used for cutting, coagulating and evaporating tissues.
Traditional methods of surgery have long included cutting tissue with mechanical knives. One of the fundamental problems with mechanical knives, however, is that they create bleeding while cutting the tissue. In addition to the unavoidable and undesirable loss of blood, there is an additional risk of not being able to stop bleeding in certain tissues such as the brain, and in certain organs such as the liver, spleen, and pancreas. Furthermore, where the object of the surgery is to remove cancerous growths, there is a risk of transferring cancer cells through the open channels, such as veins, arteries, bile ducts, or lymphatic channels, created by the mechanically cut tissue.
In general, cutting tissue with a knife can be described as applying energy with mechanical force in the form of the hard, sharp edge of the metal knife applying mechanical pressure against a thin line of a softer tissue to break the tissue locally. Energies and mechanisms in addition or instead of mechanical energy and mechanical pressure may be used in surgery, however, such as but not limited to, mechanical impact, or thermal energy mechanisms such as low-temperature freezing or high-temperature burning.
For example, for hard tissue such as bone, a saw may be used to break the bone using the mechanical impact and momentum of the hard, metal sawteeth, also creating thermal energy. Ultrasonic vibration tools also apply mechanical impact to destroy tissues that are relatively softer than the mechanical tool. Cryogenic equipment cools tissue to a freezing temperature to destroy it. Thermal energy transferred from a metal mass may be used to destroy unwanted tissues and simultaneously stop bleeding of using a burning mechanism. When the metal mass is heated with electrical energy, it is referred to as bipolar cauterizing equipment. Thermal energy can also be transferred to the tissue by electrical discharge.
Some high-temperature, thermal energy technologies include the use of electrons, ions, atoms or photons to apply the thermal energy. Monopolar cauterizing equipment transfers energy to the tissue using single electrons and ions of gas atoms. Lasers use the conversion of single photon energy in packed photons to thermal energy to hit the tissues to destroy them or to stop their bleeding.
The above energies and mechanisms may be combined, such as, for example, as is demonstrated by cryogenic or ultrasonic knives. For all of the above technologies in which a mass of matter such as a metal or plastic is used to transfer thermal energy to or from the tissues, however, a relatively large amount of energy is transferred. Technologies that use particles like electrons, ions, atoms or photons for energy transfer, on the other hand, transfer a relatively small amount of energy. For illustrative purposes, the amount of total thermal energy transferred to a tissue can be calculated as the number of atoms applied times the energy per atom, assuming that at the moment the metal or mass of matter touches the tissue, its total energy will be transferred to the tissue. Thus, the use of a cubic millimeter of titanium for heat transfer can be compared with use of the cubic millimeter of an inert gas, such as in a plasma device. One mole of argon gas weighs about 40 grams, and its volume is 22.4 liters (22,400,000 cubic millimeters), but one mole of titanium weighs about 48 grams and its volume is 10.55 cubic centimeters (10,550 cubic millimeters). Given that one mole of metal has 6.022xc3x971023 atoms, the thermal energy transferred at the moment of contact with the cubic millimeter of titanium is the thermal energy of approximately 5.7xc3x971019 atoms. A cubic millimeter of any inert gas has only 2.7xc3x971016 atoms, which is more than two thousand times less than the number of atoms in a cubic millimeter of a relatively light metal. It is typically not practically possible to apply a titanium piece to the tissue smaller than a cubic millimeter, but it is possible to make a momentary application of an inert gas to an area of tissue less than a cubic millimeter. Thus, even if the temperature of the titanium is 1000xc2x0 C. and the temperature of an inert gas is 10,000xc2x0 C., it is possible to focus the total energy applied by the gas to a thousand times less than the amount of energy applied by the metal. In any event, one can not transfer such a high per-atom or xe2x80x9cquantumxe2x80x9d energy with a metal because the metal melts once it reaches its melting temperature.
Knives, saws, bipolar surgical equipment, and ultrasonic equipment transfer thermal energy using masses of matter. The transfer of thermal energy using monopolar surgical equipment comprises the transfer of thermal energy from electrons, ions, and some of the atoms of the tissue in the treated area. This means that the total energy transferred can be controlled quite well. One of the disadvantages of monopolar equipment, however, is the technical necessity that a second pole must be connected to the body of the patient. This connection can be far away from the tissue operated, or close to it. In both cases, other tissues may be negatively affected by the electrical currents passing through those tissues. Where the second pole connection is far away from the tissue on which the operation is performed, the currents may affect a large amount of other tissues. Where the second pole connection is close, tissue closer to the operation point is affected. This makes application of monopolar technology to sensitive tissues like brain tissues essentially impossible. Additionally, particle energies transferred by electrons and ions can be quite high, on the order of 10-20 electron volts.
Using photons for energy transfer, such as with lasers, solves both the total energy control problem and per-particle energy control problem. But when the laser beam hits the tissue, individual photons are obtained and the penetration of the photons through the tissue molecules generally cannot be controlled enough to assure that there is no molecular harm to tissues far behind the application area.
In general, the application of thermal energy destroys tissues, dehydrating them by vaporizing water molecules, and destroying the bio-molecules, breaking them into smaller molecules and vaporizing a small part of them.
Plasma technology has previously been proposed for use in surgical equipment, as detailed, for example, in U.S. Pat. Nos. 3,434,476, 3,838,242; 3,938,525; and 3,991,764. A xe2x80x9cplasmaxe2x80x9d is defined as essentially xe2x80x9ca high-temperature, ionized gas composed of electrons and positive ions in such relative numbers that the gaseous medium is essentially electrically neutral.xe2x80x9d Webster""s New World College Dictionary, 3d Edition, 1997. Plasma surgical equipment, also referred to as xe2x80x9cplasma scalpels,xe2x80x9d essentially generate a small, hot gas jet that can simultaneously cut tissue and cauterize blood vessels. Such plasma devices typically use direct current (D.C.) constant voltage sources or radio frequency (rf) sources to provide the energy to the plasma. Despite early experimentation on animals, it is believed that plasma surgical equipment has not become commercially available for use on humans possibly because of technical issues relating to the relatively large size of the hand-pieces used to direct the plasma beam at the treatment area, the relatively uncontrolled high total energy, relatively uncontrolled quantum energy, and relatively uncontrolled xe2x80x9cblast effectxe2x80x9d of the plasma beam causing undesirable destruction of surrounding tissue.
Thus, there is still a need in the art to provide improved surgical cutting technology, and particularly improved plasma cutting technology and tissue evaporation (sputtering) technology for surgical applications.
One aspect of the invention comprises a surgical apparatus adapted to emit a plurality of high-energy inert gas atoms in a stream, the apparatus comprising an inert gas source and a plasma cell in communication with the inert gas source for imparting energy to the inert gas atoms. The plasma cell is defined in part by a positive electrode and a negative electrode. At least one power supply is electrically connected to the between the positive and negative electrodes. The power supply is adapted to provide (a) initially an ionization voltage between the negative and positive electrodes to initiate a plasma from the inert gas in the plasma cell, and (b) subsequently a pulsed voltage curve that limits the plasma to a predetermined energy level. The pulsed voltage curve applied on the plasma cell through an inductance coil creates a current curve and a voltage curve that are both sharkfin-shaped. The difference in voltage between the pulsed voltage curve input to the inductance coil and the sharkfin-shaped output from the coil arises from the dampening effect of the coil.
The apparatus may further comprise a hand-piece having a tubular body comprising therein the plasma cell, and a tip comprising a channel in communication with the plasma cell for emission of the inert gas atoms from the tip. A portion of the tip disposed inside the hand-piece body may comprise the positive electrode. A control system may be connected to the gas supply and to the power supply. The control system has at least one user interface and a plurality of energy settings. The control system is adapted to vary the voltage curve and the inert gas flow to provide a user-selected energy level in said plasma. The control system may comprise a programmable controller, a quantum energy control user interface connected to the programmable controller, and a total energy control user interface connected to the programmable controller.
The quantum energy control user interface may comprise a control panel with a plurality of switches, each switch corresponding to a desired quantum energy level and the total energy control user interface may comprise a start switch, a first switch for increasing power, a second switch for decreasing power, and a stop switch.
The hand-piece may have a cooling system comprising a water circulation system within the hand-piece. The hand-piece may be detachable and may comprise materials of construction adapted to be chemically or thermally sterilized. The tip may comprise an elongated, curved extension.
Another aspect of the invention comprises a method for performing a surgical procedure of cutting, cauterizing, or evaporating a portion of a body tissue, or a combination thereof, using the surgical apparatus of this invention. The method comprises providing inert gas flow into the plasma cell, initially applying from the current source an ionization voltage between the negative and positive electrodes which initiates a plasma from the inert gas in the plasma cell, and then applying from the power supply a pulsed voltage curve which sustains the plasma at a predetermined energy level. The plasma comprises a plurality of high-energy inert gas atoms, a plurality of ions, and a plurality of free electrons. The method then comprises emitting the high-energy inert gas atoms from the plasma cell and cutting, cauterizing, or evaporating the portion of body tissue, or a combination thereof, using the high-energy inert gas atoms. The method may comprise emitting only the plurality of high-energy atoms, and essentially none of the pluralities of ions or electrons from the apparatus.
Where the method comprises creating an incision in the portion of body tissue or evaporating a portion of tissue, the method may further comprise simultaneously creating a cyst wall of cauterized tissue surrounding the incision or evaporated tissue. The method may be performed with at least a portion of the hand-piece tip submerged underwater. The method may be used for general surgery, micro-surgery, endoscopic surgery, and laparoscopic surgery, and on tissues including but not limited to bones, cartilage, liver, lung, stomach, intestines, brain, muscle, and skin tissues.